In an imaging apparatus, an AF (Auto Focus) system to automatically focus is roughly classified into a contrast detection system and a phase difference detection system. The phase difference detection system is excellent in that a high-speed AF motion is possible in comparison with the contest detection system.
As the phase difference detection, system, a pupil division phase difference detection system is generally known. The pupil division phase difference detection system is a system in which pixels for phase difference detection (for focus detection) (hereinafter, referred to as phase difference detection pixels) as well as imaging pixels are provided in the same light-receiving region (imaging region) and AF measurement is performed on an imaging surface, that is, a phase difference detection signal representing an offset direction and offset amount of a focal point is obtained.
In the case where the phase difference detection pixels are incorporated in the imaging region of the solid-state imaging apparatus, it is necessary to maintain the high sensitivity characteristics of the imaging pixels and to increase the sensitivity of the phase difference detection of the phase difference detection pixels and improve the AF performance. Therefore, conventionally, regarding a light-shielding film formed with an opening corresponding to a pixel, the opening is formed to be smaller than an imaging pixel and the focal point of a microlens corresponding to a phase difference detection pixel is set to provide a front-focus state (e.g., see Patent Document 1). Here, the “front-focus state” means a state in which the focal point is offset to the front with respect to a subject.
Patent Document 1: Japanese Patent Application Laid-open No. 2009-109965